ANTIBIOTIC BIOSYNTHESIS: The role of pantetheine in the elongation of the peptide chain in tyrocidine synthesis will be studied in further detail. In beginning a study of subtilin, synthesized in a B. subtilis, an approach will be made towards the biosynthesis of a rather longer chain of 27 amino acids in an antibiotic polypeptide which probably is made by a ribosomal pathway. The cross-linking in this polypeptide, probably post-ribosomal, between hydroxy amino acids and cysteine to form lanthionine, is of particular interest. GUANOSINE 5', 3'-POLYPHOSPHATES: Mechanisms of their biosynthesis will be continued with the findings by Dr. Sy of an unusual exclusive nonribosomal synthesis of these compounds in several bacilli. We have become interested in a newly discovered participation of GTP in protein synthesis, namely, in the so-called capping reaction of mRNA by the blocking of the 5'-terminal by reaction with GTP in forming a polyphosphate bridge between the guanosine phosphate and the 5'-terminal phosphate or phosphates of mRNA. We aim at the study of the mechanism in normal cells and progress is slowly being made in exploring the reaction in rat liver homogenates. A new enterprise was begun with a study of the well known increase of glucose uptake in chicken fibroblasts, normal ones depending on the rate of growth, and particularly when transformed with Rous sarcoma virus. We want to isolate proteins involved in glucose uptake and have made progress by finding a glucose binding protein in homogenates that shows different characteristics in normal and transformed cells.